1. Technical Field
The present invention relates to an image generating device, an image generating method and a printing device.
2. Prior Art
With the evolving high performance of document preparation systems and document printing systems using computers in recent years, there are increasing desires of users for realizing complicated expression in drawing. For example, gradation (gradually changing the color in a prescribed drawing area) is being used a lot for effective presentation, for expressing three-dimensional shapes, etc.
In order to print such a gradation (i.e. an image having gradation) with a printer or display such a gradation on a display, it is necessary to generate a gradation pattern in the bitmap format and draw the gradation pattern on a page memory or frame memory.
In conventional techniques, the drawing of a gradation is carried out by successively drawing (overlaying) multiple areas slightly differing in the color value while gradually shifting the drawing position of each area. For example, in order to draw a gradation in which the color changes smoothly in a pattern like concentric circles, a large circle is drawn first and filled in with a prescribed color. Subsequently, a slightly smaller circle is drawn in (overlaid on) the previously drawn (filled) circle and filled in with a different color. The process is repeated many times until the drawing position (currently drawn circle) gets close enough to the center of the concentric circles (see Japanese Patent Provisional Publication No. HEI 11-31231 (hereinafter referred to as a “patent document #1”), for example).